The present invention relates to a device for protecting at least one pipe located at the bottom of a body of water, comprising a plurality of disconnected ballast elements for the pipe, each ballast element having a lower surface intended to be placed on the bottom of a body of water and an upper surface defining at least one trough for supporting the pipe.
Such a device is in particular applicable to the protection of fluid transport pipes laid at the bottom of a body of water, such as a sea, an ocean or a lake.
The pipe is intended in particular to transport a fluid, such as hydrocarbons, gases, or mixtures and gases and fluids, for example, between a wellhead situated on the bottom of the body of water and a convergence zone where several pipes come together. The fluids collected in the convergence zone rise toward a surface facility via one or more riser pipes.
Offshore hydrocarbon production fields are known that comprise a multitude of wellheads and therefore a large number of transport pipes extending on the sea bottom.
It is therefore sometimes necessary to immobilize said pipes relative to each other on the sea bottom, to prevent them from moving under the effect of underwater currents and to prevent them from damaging the neighboring pipes or the underwater equipment.
To that end, it is known to provide the pipe with passive ballast elements that make it possible to stabilize the position of the pipe on the sea bottom, using the foundry weight of the ballast elements.
These ballast elements are for example made up of a concrete covering surrounding the entire length of the pipe or annular concrete elements distributed at intervals along the pipe, as described for example in French application FR-A-2 400 657, or in U.S. Pat. No. 3,240,512.
Such a device has a very large mass, however, which complicates the handling and installation of the pipe at the bottom of the body of water.
Furthermore, such a device ensures only partial protection of the pipe, in particular against impacts caused by falling objects or underwater operations.
This protection may prove necessary, however, in particular in the context of the transportation of cryogenic liquids, such as liquefied natural gases (LNG), which are kept at a temperature near −160° C.
In that case, the pipes used have a dual insulating housing, the integrity of which must be protected to ensure completely safe transport of the fluid.